package top.myegg.wx.util;

import java.security.MessageDigest;
import java.util.Arrays;

public class WeChatTools {
	
	// 与接口配置信息中的Token要一致   
	private static final String token = "stephen";
	
	public static boolean checkSignature(String signature, String timestamp, String nonce){
		String[] arr = new String[] {token,timestamp ,nonce};
		Arrays.sort(arr);
		StringBuilder content = new StringBuilder();
		
		for(int i=0; i<arr.length; i++){
			content.append(arr[i]);
		}
		
		//sha1加密
		String tmpStr = getSha1(content.toString());
		
		// 将sha1加密后的字符串可与signature对比，标识该请求来源于微信  
		return tmpStr.equals(signature);
	}
	
	//sh1加密
	public static String getSha1(String str){
        if(str==null||str.length()==0){
            return null;
        }
        char hexDigits[] = {'0','1','2','3','4','5','6','7','8','9',
                'a','b','c','d','e','f'};
        try {
            MessageDigest mdTemp = MessageDigest.getInstance("SHA1");
            mdTemp.update(str.getBytes("UTF-8"));

            byte[] md = mdTemp.digest();
            int j = md.length;
            char buf[] = new char[j*2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                buf[k++] = hexDigits[byte0 >>> 4 & 0xf];
                buf[k++] = hexDigits[byte0 & 0xf];      
            }
            return new String(buf);
        } catch (Exception e) {
            // TODO: handle exception
            return null;
        }
    }
	
}
